Trying to parse a URL with this format http://landing.com?data=123 - I'm been able to get the Data through irb like:
require "addressable/uri"
uri = Addressable::URI.parse("http://landing.com?data=123")
uri.query_values['data']
=> '123'
But I'm stuck on how to interact with that 'data' within a Rails view. I have tried including it in Controller (pages_controller.rb in my sample) like:
class PagesController < InheritedResources::Base
def test
uri = Addressable::URI.parse("<%= request.original_url %>")
u = uri.query_values['data']
end
end
But no idea how can I extract that piece of data to be used within my Views. Any guidance on this?
If I open one of the views like where I call that 'test' method - I'm getting uninitialized constant PagesController::Addressable but made sure it's in my enviroment with gem which addressable/uri
Controllers have a lot of the query information already parsed. You can access it with params. In that case, you can use
u = params[:data]
As Sophie Déziel said, if it's under an app request, you can access to your query values through params hash. params is present in your controllers and views.
If you are talking about hardcoded URLs or URLS that you get from 3rd party sources, you will nee to create an instance variable in your controller (#u = ...) to be available in your views.
Note that you're not supposed to call action methods in your views, they are 'invoked' by Rails framework.
# controller
def my_action
# .....
#u = uri.query_values['data']
end
# view
<%= #u %>
Related
I have ruby on rails app and my controller should process request which creates many objects. Objects data is passed from client via json using POST method.
Example of my request (log from controller):
Processing by PersonsController#save_all as JSON
Parameters: {"_json"=>[{"date"=>"9/15/2014", "name"=>"John"},
{"date"=>"9/15/2014", "name"=>"Mike"}], "person"=>{}}
So i need to save these two users but i have some issues:
How to verify strong parameters here? Only Name and Date attributes can be passed from client
How can I convert String to Date if i use Person.new(params)?
Can i somehow preprocess my json? For example i want to replace name="Mike" to name="Mike User" and only then pass it in my model
I want to enrich params of every person by adding some default parameters, for example, i want to add status="new_created" to person params
First of all I'd name the root param something like "users", then it gives a structure that is all connected to the controller name and the data being sent.
Regarding strong params. The config depends of your rails app version. <= 3.x doesn't have this included so you need to add the gem. If you're on >= 4.x then this is already part of rails.
Next in your controller you need to define a method that will do the filtering of the params you need. I should look something like:
class PeopleController < ApplicationController
def some_action
# Here you can call a service that receives people_params and takes
# care of the creation.
if PeopleService.new(people_params).perform
# some logic
else
# some logic
end
end
private
def base_people_params
params.permit(people: [:name, :date])
end
# Usually if you don't want to manipulate the params then call the method
# just #people_params
def people_params
base_people_params.merge(people: normalized_params)
end
# In case you decided to manipulate the params then create small methods
# that would that separately. This way you would be able to understand this
# logic when returning to this code in a couple of months.
def normalized_params
return [] unless params[:people]
params[:people].each_with_object([]) do |result, person|
result << {
name: normalize_name(person[:name]),
date: normalize_date(person[:date]),
}
end
end
def normalize_date(date)
Time.parse(date)
end
def normalize_name(name)
"#{name} - User"
end
end
If you see that the code starts to get to customized take into a service. It will help to help to keep you controller thin (and healthy).
When you create one reason at the time (and not a batch like here) the code is a bit simpler, you work with hashes instead of arrays... but it's all pretty much the same.
EDIT:
If you don't need to manipulate a specific param then just don't
def normalized_params
return [] unless params[:people]
params[:people].each_with_object([]) do |result, person|
result << {
name: person[:name],
date: normalize_date(person[:date]),
}
end
end
I'm real beginner in Rails.
I created app/services/xclass.rb class with some_method inside.
I need to execute some_method using url.
For example, I want run this method when I execute in my browser url - http://application.com/notifications/send
I think it could be done through controller (notifications_controller) but how to do it?
I created only controller, with no model, just for launching some_method.
first, create a route:
get "notifications/send" => "notifications#some_action", :as => "send_notification"
Then create a controller action in your controller (ie. NotificationsController):
def some_action
Xclass.some_method # run the method you want
redirect_to root_path # redirect or whatever you want here
end
Now you can either visit the path http://your_app.com/notifications/send, or link to is using 'send_notifications_path' url helper in rails.
That should do it
Since you're a beginner, let me give you some ideas
MVC
Firstly, you need to appreciate that Rails is an MVC (model view controller) framework:
In short, this means that every time you send a "request" to Rails, it will be "routed" to the specific controller action which corresponds with that route.
This means that when you ask about how to fire a "class method", you're going to have to work within the confines of the MVC programming pattern. Here's how:
#config/routes.rb
resources :notifications do
get :send, on: :collection #=> domain.com/notifications/send
end
#app/controllers/notifications_controller.rb
class NotificationsController < ApplicationController
def send
#call your class method here
YourModel.class_method
end
end
#app/lib/your_model.rb
class YourModel
def self.class_method
#do something here
end
end
--
Rails
This is further supported by the fact that Rails is just a framework - in fact it's a gem (a great one) which runs on top of Ruby.
This means that even though some of the ways in which Rails works might seem somewhat alien to begin with, you have to remember that it basically just captures "requests" fed to it by a web sever, processing them with connectivity to the database etc.
The issue here is that as you're sending the request over HTTP, you have to work within the constraints of this protocol (specifically that it's stateless), and with Rails. As mentioned, Rails is MVC-based, which means that every request will be routed to your controller, which is why you have to create the corresponding route & controller action to handle it
If you use the code above (tweaked to your app), it should work for you
I am facing an issue with accessing a particular variable of a method say A , in another method say B in the controller.. The size of the object(variable) is too big since it contains the results of a service call made.. My usecase is like on selecting an option from a drop down box, it redirects to a method B in controller and the same object(variable) should be parsed. How can I access the variable in the other method?
I tried storing in a cookie and since the size is too big I am getting Cookie Overflow exception. I am not using a DB. So I guess using memcache won't work. Also tried storing it as hidden field in view and passed its value as a data through ajax call. But I am getting it as a string. Tried to specify datatype as json and several other ways.. but of no use..Using ##var also din work..Not sure why..
Code:
On change of the drop down:
$(document).ready(function(){
$('#filter_service').change(function() {
$.ajax({type: "GET",
url: "/device_troubleshootings/query_operation",
data: { filter_service: $('# filter_service').val()},
});
});
});
Service call:
def log_results
//Service call
#get_log_results = LogQueryService.client.get_logs(Com::Amazon::Logqueryservice::DeviceSerialNumberQuery.new(:search_text => # search , :index => 'dms', :index_type => '_all', :from_time_stamp => #from_time_stamp, :to_time_stamp => #to_time_stamp))
#dsn_result = #get_log_results.logs_result_obj_list
end
Here, I am trying to access #dsn_result object in "/device_troubleshootings/query_operation” method.
Please suggest me ways to access the variable.
MVC
I think you're getting confused with how Rails should work
Remember, Rails (which is just a framework for Ruby) is built on the "MVC" programming pattern. This means each time you send a request to your Rails application, it has to be handled by a single controller#action which you will then allow you to pull the relevant data from your models
The problem you have is you're trying to load multiple controller methods, and pass the same data to both. This might work in Ruby, but not Rails (Rails is stateless):
--
Model
The correct way to handle this type of setup is by creating another request for your application, which will load another controller#action, allowing you to access the data you need
As demonstrated by the MVC diagram above, each time you send a request to Rails, it's basically a new request. This means that unless you've persisted your data in the likes of a cookie, you'll need to load the data from the model.
The problem you have is you're trying to store an entire data-set in the front-end of your system. This issue is very bad, as not only is it inefficient, but it goes against the MVC pattern completely.
You'll be much better storing the bare-minimum data set you need in the front-end (ids or similar), which you will then be able send to your controller via ajax; building a new data-set from
--
Class Variables
You mentioned you tried to declare some ##class variables to no avail. The problem with this is that the class vars will only be available for an instance of a class.
As mentioned, since Rails is stateless, the class variables won't persist between requests (how can they?). I think you know this already, considering you've been trying to use cookies to store your data
The way to resolve this is to rebuild the data each time from the model (as detailed above)
Solution
The solution for you is to "go stateless"
Here's how:
Treat Method A and Method B as completely separate "ACTIONS"
When using these actions, you need to consider the smallest piece of data to pass between the two
To load Method B, you need to send a new request from your browser (as if you've never loaded Method A before)
Your method_a can be handled in the "standard" way:
#config/routes.rb
resources :your_controller do
collection do
get :method_a
get :method_b
end
end
This will mean that you can load method_a relatively simply:
#app/controllers/your_controller.rb
Class YourController < ApplicationController
def method_a
#get_log_results = LogQueryService.client.get_logs(Com::Amazon::Logqueryservice::DeviceSerialNumberQuery.new(:search_text => # search , :index => 'dms', :index_type => '_all', :from_time_stamp => #from_time_stamp, :to_time_stamp => #to_time_stamp))
#dsn_result = #get_log_results.logs_result_obj_list
end
end
As you know, the #dsn_result will not persist through to the next request.
There are two ways to resolve this (set a CONSTANT -- if you're pulling from an API, this will give you a single call -- or use a before_action to set the variable for as many actions as you need). I'll detail both for you:
#app/controllers/your_controller.rb
Class YourController < ApplicationController
before_action :set_log_data
def method_a
end
def method_b
end
private
def set_log_data
#get_log_results = LogQueryService.client.get_logs(Com::Amazon::Logqueryservice::DeviceSerialNumberQuery.new(:search_text => # search , :index => 'dms', :index_type => '_all', :from_time_stamp => #from_time_stamp, :to_time_stamp => #to_time_stamp))
#dsn_result = #get_log_results.logs_result_obj_list
end
end
This will work if you pull data from your own data-set (using the models), however, the better way to do this in your case will likely be to set a constant (considering, of course, that you don't want the data to change):
#config/initializers/dsn_result.rb
get_log_results = LogQueryService.client.get_logs(Com::Amazon::Logqueryservice::DeviceSerialNumberQuery.new(:search_text => # search , :index => 'dms', :index_type => '_all', :from_time_stamp => #from_time_stamp, :to_time_stamp => #to_time_stamp))
DSN_RESULT = get_log_results.logs_result_obj_list
In my case I solved with global variable $my_global_var
So my files look like this
routes.rb
Rails.application.routes.draw do
resources :pages
root 'pages#index'
post 'pages/test'
end
pages_controller.rb
class PagesController < ApplicationController
def firstaction
$my_global_var = "My global var"
puts $my_global_var
end
def secondaction
puts $my_global_var
end
end
index.html.erb
<%= button_to 'Test', pages_test_path, method: :post %>
As title says, why does Rails prefer to use the #params variable inside of a Controller action when you are responding to the action instead of passing the individual parameters through the function arguments when we call the function?
Other frameworks use this (i.e, ASP MVC) and I was just wondering if there was a reason for that design decision, because it doesn't seem very intuitive.
Ie. Why does Rails do
def index
name = params[:name]
end
Instead of
def index(name)
end
The point is, most of the actions in a controller handles the view REST-fully. The params comes from the user's browser when they interact with the page or send a new variable request to the page.
These requests are variable, and Rails makes it uniform by maintaining the parameters in params hash. If the following GET requests arrive:
http://localhost:3000/products?color=red&quality=best
the params hash will automatically be populated as {'color' => 'red', 'quality' => 'best'}. Rails doesn't expect your action to manually handle the parameters.
Similarly, consider you are getting a POST request from a page where a user filled a form. In that scenario, the params obtain the parameters which are composed with form helpers inside views.
Though in hyptothetical case you are dealing with general methods instead of actions, such as below, you will have to do it by passing arguments.
def show
if params['color'] == 'red'
#product = obtain_product('red')
else
#,..
end
end
def obtain_product(color)
Product.where('color = ?', color).first
end
Hope it is clear. :)
#kidorrails has a great answer, and I wanted to add to it:
If you wanted to pass the params to each method directly, it would go against the #1 Rails convention - keep it DRY. By having a separate params hash, you not only have access to all the params you want, but you can access them through as many methods as you need
For example, take strong_params:
#controller
def new
#model = Model.new
end
def create
#model = Model.new(strong_params)
#model.save
end
private
def strong_params
params.require(:model).permit(:your, :params)
end
As #apneadiving mentioned, the params hash is created in another part of the stack, meaning it's available over all the methods required. It's most efficient & versatile way to do it IMO
I'm trying to sort out the routing for a multinational web store which only has a presence in certain countries. Each store is different and has a different catalogue of products and there is also a world-wide store for all other countries. I have set up Nginx to prepend the two letter country code from an lookup of the user's IP address so that my Rails app can figure which store to direct the visitor to. I then use Sven Fuch's excellent routing-filter to capture that code, do a lookup against a global SHOPS object and if a match is found then the country code is used, otherwise they get the default (world-wide) store. My routing filter currently looks like this:
module RoutingFilter
class Country < Filter
countries_pattern ||= %r(^/(?i)([a-zA-Z]{2})(?=/|$))
def around_recognize(path, env, &block)
country = "#{extract_segment!(countries_pattern, path)}".upcase
yield(path, env).tap do |params|
params[:shop] = SHOPS.fetch(country.to_sym) || DEFAULT_SHOP
end
end
def around_generate(params, &block)
puts params
shop = params.delete(:shop)
yield.tap do |result|
prepend_segment!(result, shop[:country_code]) if shop
end
end
end
end
Now the curious thing is, the params collection does not contain a :shop param when the around_generate method is executed. My code is directly based on the pagination filter included with the routing-filter gem (I'm not using the locale filter as each of these stores is also multilingual - i18n is handled using accept-language header instead). The original pagination filter by Sven Fuchs looks like this:
module RoutingFilter
class Pagination < Filter
PAGINATION_SEGMENT = %r(/page/([\d]+)/?$)
def around_recognize(path, env, &block)
page = extract_segment!(PAGINATION_SEGMENT, path)
yield(path, env).tap do |params|
params[:page] = page.to_i if page
end
end
def around_generate(params, &block)
page = params.delete(:page)
yield.tap do |result|
append_segment!(result, "page/#{page}") if append_page?(page)
end
end
protected
def append_page?(page)
page && page.to_i != 1
end
end
end
In my filter, shop = params.delete(:shop) results in a Nil object error and I can see from "puts params" that it is indeed not present. Does anyone have any suggestions as to why I'm unable to store and retrieve the :shop param?
Edit: I should mention that I have checked that the parameter gets set correctly in around_recognize - a "puts" of the params collection here does indeed contain the correct :shop object.
If you don't pass a :shop param to url_for (or whatever url generation helper you use here) it won't be passed to around_generate either. around_generate wraps around the url generation part of the routing system.
The Pagination filter assumes the same, e.g. it would be called like blog_posts_path(:page => 2).
But maybe that's not what you want. If you have a look at the Locale filter then this assumes that you sometimes pass a locale to the url helper but sometimes you don't. If :locale is not given it will look it up from I18n.locale which is the current locale set for this request. Maybe you want something similar here?
You could also have a look at the controller's default_url_options. IIRC you can set a default option here, too, so maybe this could work for you. I'm not using this approach anywhere though, so I'm just guessing.
HTH